The invention relates generally to surgical instruments, and more specifically, is directed to cryogenic-and-ultrasonic scalpels, having particular applicability to surgery on soft tissues and parenchymatous organs, such as the liver, pancreas, kidneys, lungs, spleen, as well as in neurosurgery.
Conventional cryosurgery is directed to the use of cryogenic temperatures to freeze various tissues to destroy the tissues. However, a scalpel is generally not involved.
Thus, known in the present state of the art are cryogenic-and-ultrasonic surgical instruments, and in particular, probes which include a mechanism that joins the working portion with a source of ultrasonic vibrations, a jacket for refrigerant to pass, the jacket being interposed between the instrument base and the source of ultrasonic vibrations, and a nozzle located at the refrigerant inlet of the instrument. An example of such an instrument is described in USSR Inventor's Certificate No. 460,869.
However, the instrument is unsuitable for surgery since it is not capable of dissecting tissues, that is, there is no scalpel. Specifically, the disadvantages of such known instrument result in a low hemostatic effect due to rapid increases in the temperature of the working portion. This is caused by the fact that the base area of the instrument through which coolant streams pass, is substantially less than the area of the lateral surfaces of the working portion through which lateral surfaces heat streams pass. In addition, the heat exchanger, provided on the mechanism that connects the operating instrument with the source of ultrasonic vibrations, contributes to a decrease in the amplitude of the ultrasonic vibrations in the working portion, which causes tissue sticking to the blade and leads to a decrease in the hemostatic effect.
There is also known a cryogenic-and-ultrasonic scalpel comprising a body accommodating a source of ultrasonic vibrations, a blade connected to the source of ultrasonic vibrations through a transformer and a tubular heat exchanger for supplying refrigerant to the blade. The heat exchanger is fashioned as a U-shaped tube for providing thermal contact with the lateral surface of the blade and is connected to a refrigerant supply and removal pipes that extend through bellows located within the zone of a standing wave arising when the blade is connected to the source of ultrasonic vibrations. The tubes of the heat exchanger taper towards the cutting edge of the scalpel. An example of such an instrument is described in USSR Inventor's Certificate No. 825,056.
This instrument, however, also suffers from certain disadvantages. Specifically, disadvantages inherent in such a cryogenic-and-ultrasonic scalpel result in a low hemostatic effect and an inadequate tissue dissection rate during surgery on soft tissues and parenchymatous organs such as the liver or pancreas, due to too low refrigerating capacity of the U-shaped tubular heat exchanger. These disadvantages stem from the fact the blade features direct and thermal contact with the transformer at the point of their interconnection. In this case, a considerable part of the heat evolved by the transformer and the source of ultrasonic vibrations due to the large conversion loss of electric ultrasonic power into mechanical energy, is imparted to the blade, thus causing its temperature to rise. As a result, the refrigerating capacity of the U-shaped heat exchanger which is in thermal contact not only with the blade but also with the abundantly blood-supplied organ being operated on such as the liver, is insufficient, particularly in cases of prolonged surgery, thus causing tissue sticking to the blade, a reduced tissue dissection rate and an adversely affected hemostatic therapeutic effect. Moreover, the U-shape of the heat exchanger pipes that supplies the refrigerant renders the instrument too unwieldy, and hence, inconvenient in operation. In other words, the cryogenic material is passed over one side of the scalpel and is withdrawn after passing to the opposite side of the scalpel.
U.S. Pat. Nos. 4,528,979; 3,942,519; and 3,911,924 disclose cryogenic and ultrasonic destructors or probes. U.S. Pat. No. 3,622,755 discloses a cryogenic surgical blade. U.S. Pat. Nos. 3,888,004; 3,794,040; and 2,714,890 disclose ultrasonic blades. Other patents of interest are U.S. Pat. Nos. 3,786,814; 3,636,943; 3,918,442; and 4,609,368; and USSR Inventor's Certificates Nos. 556,797 and 1,153,901.